Renewable transportation fuels from biological sources (biofuels) offer a sustainable alternative to current fossil sources. Biofuel has a tremendous advantage relative to fossil fuels since the production and use of biofuels can be carbon neutral. Bioethanol and fatty acid methyl ester (FAME) are the main renewable transportation fuels commercially available. Despite the interest, production of renewable transportation fuels like FAME has found little integration into existing refineries due to compatibility issues and processing bottlenecks.
For a good transportation fuel, renewable diesel should have at least some of the desired hydrocarbon constituents of petro diesel. BHD obtained by reaction of glycerides, such as triglycerides, with hydrogen at high temperature and pressure to produce liquid alkanes offers similar or better quality diesel fuel as compared to petro diesel and FAME. The BHD platform also provides raw material flexibility, accommodating a variety of oils sources, including numerous vegetable oils, such as oils derived from palm, jatropha, canola, and others.
The current state of BHD production is based on large scale batch reactor systems. These reactor systems have several major disadvantages, such as mass and heat transfer limitations, which result in inefficient use of catalyst and large energy requirements. Similarly, in conventional multiphase reactors, which are typically fluidized bed or fixed bed reactors, reactions are limited by mass transfer due to the relatively low specific interfacial area attained by these reactor designs. There is in an inherent limitation in the rate of mass transfer between the bulk phase and the catalyst surface, limiting the overall efficiency such reactors can achieve.
A need therefore exists for an efficient, compact, continuous, and scalable apparatus, and method for using such apparatus, to produce BHD and similar products.